Transmission unit, power transmission system and vehicle comprising the same

ABSTRACT

A transmission unit includes: input shafts, each of the input shafts being provided with a shift driving gear thereon; output shafts, each of the output shafts being provided with a shift driven gear configured to mesh with a corresponding shift driving; a motor power shaft configured to rotate together with one of the output shafts; and an output unit configured to rotate with one of the output shafts at different speeds and configured to selectively engage with one of the output shafts so as to rotate together with one of the output shafts. A power transmission system including the transmission unit and a vehicle including the power transmission system are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and benefits of Chinese PatentApplication Nos. 201510024215.1 and 201520033266.6, both filed with theState Intellectual Property Office of P. R. China on Jan. 16, 2015. Theentire contents of the above-identified applications are incorporatedherein by reference.

FIELD

Embodiments of the present disclosure relate to vehicles, and moreparticularly to a transmission unit, a power transmission systemincluding the transmission unit, and a vehicle including the powertransmission system.

BACKGROUND

To reduce energy consumption, the development and utilization ofenergy-efficient vehicles have become a trend. As an energy-efficientvehicle, a hybrid vehicle is driven by at least one of an internalcombustion engine and a motor and has various operation modes, andconsequently may operate with improved transmission efficiency and fuelefficiency.

However, in the related art, the power transmission system in the hybridvehicle is generally complex in structure, provides fewer transmissionmodes, and is low in transmission efficiency. Besides, for most hybridvehicles, the charging process is always carried out during the runningof the vehicle. Therefore, a conventional hybrid vehicle has relativelyfewer charging modes and charging passage, and lower chargingefficiency.

SUMMARY

Embodiments of the present disclosure seek to solve at least one of theproblems existing in the prior art to at least some extent.

Embodiments of a first broad aspect of the present disclosure provide atransmission unit. The transmission unit according to embodiments of thepresent disclosure includes: a plurality of input shafts, each of theinput shafts being provided with a shift driving gear thereon; aplurality of output shafts, each of the output shafts being providedwith a shift driven gear configured to mesh with a corresponding shiftdriving gear; a motor power shaft configured to rotate together with oneof the output shafts; and an output unit configured to rotate with oneof the output shafts at different speeds and configured to selectivelyengage with one of the output shafts so as to rotate together with oneof the output shafts.

Embodiments of a second broad aspect of the present disclosure provide apower transmission system including the transmission unit. The powertransmission system including the transmission unit according toembodiments of the present disclosure includes the above-identifiedtransmission unit and a first motor generator configured to rotatetogether with the motor power shaft.

Embodiments of a third broad aspect of the present disclosure provide avehicle. The vehicle according to embodiments of the present disclosureincludes the above-identified power transmission system for a vehicle.

With the power transmission unit and the power transmission systemaccording to embodiments of the present disclosure, the transmissionmodes are increased, and various conditions, such as charging thevehicle while parking or charging the vehicle while driving, may beaccomplished.

Additional aspects and advantages of embodiments of present disclosurewill be given in part in the following descriptions, become apparent inpart from the following descriptions, or be learned from the practice ofthe embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and advantages of embodiments of the presentdisclosure will become apparent and more readily appreciated from thefollowing descriptions made with reference to the accompanying drawings,in which:

FIG. 1 is a schematic view of an exemplary power transmission systemaccording to an embodiment of the present disclosure;

FIG. 2 is a schematic view of an exemplary power transmission systemaccording to an embodiment of the present disclosure;

FIG. 3 is a schematic view of an exemplary power transmission systemaccording to an embodiment of the present disclosure;

FIG. 4 is a schematic view of an exemplary power transmission systemaccording to an embodiment of the present disclosure;

FIG. 5 is a schematic view of an exemplary power transmission systemaccording to an embodiment of the present disclosure; and

FIG. 6 is a schematic view of an exemplary power transmission unit of apower transmission system according to an embodiment of the presentdisclosure.

DETAILED DESCRIPTION

Reference will be made in detail to embodiments of the presentdisclosure. The embodiments described herein with reference to drawingsare explanatory, illustrative, and used to generally understand thepresent disclosure. The embodiments shall not be construed to limit thepresent disclosure. The same or similar elements and the elements havingsame or similar functions are denoted by like reference numeralsthroughout the descriptions.

In the specification, it should be understood that, the terms such as“central”, “longitudinal”, “lateral”, “width”, “thickness”, “above”,“below”, “front”, “rear”, “right”, “left”, “vertical”, “horizontal”,“top”, “bottom”, “inner”, “outer”, “clockwise”, “counter-clockwise”should be construed to refer to the orientation as then described or asshown in the drawings. These terms are merely for convenience andconcision of description and do not alone indicate or imply that thedevice or element referred to must have a particular orientation. Thus,it cannot be understood to limit the present disclosure.

In addition, terms such as “first” and “second” are used herein forpurposes of description and are not intended to indicate or implyrelative importance or significance or impliedly indicate quantity ofthe technical feature referred to. Thus, the feature defined with“first” and “second” may comprise one or more these features. In thedescription of the present disclosure, “a plurality of” means two ormore than two these features, unless specified otherwise.

In the present invention, unless specified or limited otherwise, theterms “mounted,” “connected,” “coupled,” “fixed” and the like are usedbroadly, and may be, for example, fixed connections, detachableconnections, or integral connections; may also be mechanical orelectrical connections; may also be direct connections or indirectconnections via intervening structures; may also be inner communicationsof two elements, which can be understood by those skilled in the artaccording to specific situations.

In the present invention, unless specified or limited otherwise, astructure in which a first feature is “on” or “below” a second featuremay include an embodiment in which the first feature is in directcontact with the second feature, and may also include an embodiment inwhich the first feature and the second feature are not in direct contactwith each other, but are contacted via an additional feature formedtherebetween. Furthermore, a first feature “on,” “above,” or “on top of”a second feature may include an embodiment in which the first feature isright or obliquely “on,” “above,” or “on top of” the second feature, orjust means that the first feature is at a height higher than that of thesecond feature; while a first feature “below,” “under,” or “on bottomof” a second feature may include an embodiment in which the firstfeature is right or obliquely “below,” “under,” or “on bottom of” thesecond feature, or just means that the first feature is at a heightlower than that of the second feature.

A power transmission system according to embodiments of the presentdisclosure may be described below with reference to FIGS. 1-5. The powertransmission system according to embodiments of the present disclosuremay be used in vehicles such as hybrid vehicles as a power system, whichmay provide sufficient power and electric power for driving the vehicle.

In some embodiments, a power transmission system 100 may generallyinclude a power unit and a transmission unit. The power unit may be anengine 4, a motor generator, and so on. In some embodiments, thetransmission unit 101 as shown in FIG. 6 may transmit power output fromthe power unit, thus driving or charging the vehicle.

In some embodiments, as shown in FIGS. 1-5, the power transmissionsystem 100 may include but is not limited to an engine 4, a first motorgenerator 51 and a transmission unit 101.

In some embodiments as shown in, for example, FIG. 1, the transmission101 unit includes a plurality of input shafts (e.g., a first input shaft11, a second input shaft 12), a plurality of output shafts (e.g., afirst output shaft 21, a second output shaft 22), a motor power shaft 3,a plurality of gears provided on related shafts (such as the inputshaft, the output shaft, and the motor power shaft), and a gear shiftmember such as a synchronizer.

In some embodiments, the engine 4 is configured to selectively engagewith at least one of the input shafts, when the engine 4 performs powertransmission with the input shaft(s). For example, when the engine 4 istransmitting power to the input shaft, the engine 4 may selectivelyengage with one of the input shafts to transmit power. In someembodiments, the engine 4 may be selectively engaged with two or more ofthe input shafts simultaneously to transmit power.

In some embodiments, as shown in FIGS. 1-5, the plurality of inputshafts include a first input shaft 11 and a second input shaft 12. Theengine 4 may selectively engage with one of the first and second inputshafts 11, 12 to transmit power. In some embodiments, the engine 4 mayengage with the first and second input shafts 11, 12 simultaneously totransmit power. It should be noted that the engine 4 may be disengagedfrom the first and second input shafts 11, 12 simultaneously.

It is known to a person skilled in the art that the engagement betweenthe engine 4 and the input shaft(s) is related to specific conditions ofthe power transmission system 100. The engagement between the engine 4and the input shaft(s) will be described below in detail with referenceto detailed embodiments.

In some embodiments, the power transmission between the input shaft(s)and the output shaft(s) is achieved by shaft gear pairs. For example,each of the input shafts has a shaft driving gear provided thereon, eachof the output shafts has a shaft driven gear provided thereon, so that aplurality of gear pairs with different velocity ratios are formed bymeshes of corresponding shaft driving gears and shaft driven gears.

In some embodiments, the transmission unit may be a six-speedtransmission, i.e. the transmission unit may include a first-gear gearpair, a second-gear gear pair, a third-gear gear pair, a fourth-geargear pair, a fifth-gear gear pair and a sixth-gear gear pair. There areno particular limits in the present disclosure, a person skilled in theart may increase or reduce the number of gear pairs accordingly based ontransmission requirements, and the transmission unit may not be limitedto the six-speed transmission as disclosed in the present embodiment.

In some embodiments, as shown in, for example, FIGS. 1-6, the motorpower shaft 3 is configured to rotate together with one of the outputshafts, such as the second output shaft 22. In some embodiments, whenpower (such as power transmitted to an output shaft from the engine 4)needs to be transmitted to the motor power shaft 3, the motor powershaft 3 can rotate together with the output shaft while receiving thepower. In some embodiments, when power (such as power transmitted to themotor power shaft 3 from a first motor generator 51) needs to betransmitted to an output shaft, this output shaft can rotate togetherwith the motor power shaft 3 while receiving power.

In some specification of the present disclosure, the expression “rotatetogether with” means that related components (such as two components)may rotate together. In an embodiment that one component rotatestogether with the other one component, when the one component rotates,the other one component rotates together.

In some embodiments where a gear rotates together with a shaft, when thegear rotates, the relative shaft rotates together; alternatively, whenthe shaft rotates, the relative gear rotates together.

In some embodiments where one shaft rotates together with the othershaft, when one shaft rotates, the other shaft rotates together.

In some embodiments where one gear rotate together with the other onegear, when the one gear rotates, the other one gear rotates together.

In the following description, the expression “rotate together with” maybe understood as described above, unless specified or limited otherwise.

In some embodiments, the first motor generator 51 may be configured torotate together with the motor power shaft 3. For example, whenfunctioning as a motor, the first motor generator 51 outputs the powerto the motor power shaft 3. In some embodiments, when functioning as agenerator, power from the motor power shaft 3 may be transmitted to thefirst motor generator 51, thereby driving the first motor generator 51to generate electric power.

In the specification of the present disclosure, a motor generator (suchas the first motor generator 51) may be understood as an apparatus whichcan function as a motor and a generator, unless specified or limitedotherwise.

In some embodiments, the motor power shaft 3 may rotate together withone of the output shafts, such as the second output shaft 22. In someembodiments, when the motor power shaft 3 is rotating together with theone of the output shafts, the first motor generator 51 may use at leasta part of power output by the engine 4 so as to generate electric powerwhen the vehicle is parking or running.

In some embodiments, when the vehicle is in a running state and themotor power shaft 3 is rotating together with one of the output shafts,a part of power output by the engine 4 may be transmitted to the firstmotor generator 51 via the motor power shaft 3 such that the first motorgenerator 51 is driven to generate electric power, thus accomplishing acondition of charging the vehicle battery while driving the vehicle. Insome embodiments, when the vehicle is in a parking state (e.g., thevehicle stops running but the engine is still working) and the motorpower shaft 3 is rotating together with one of the input shafts, a partof power output by the engine 4 may be transmitted to the first motorgenerator 51 via the motor power shaft 3 such that the first motorgenerator 51 is driven to generate electric power, thus accomplishing acondition of charging the vehicle while parking (such as charging thevehicle while the vehicle is not running).

In some embodiments, the motor power shaft 3 may be a motor shaft of thefirst motor generator 51. In some embodiments, the motor power shaft 3may be a shaft different from the motor shaft of the first motorgenerator 51.

With the power transmission system 100 according to embodiments of thepresent disclosure, the number of charging modes of the vehicle can beincreased. For example, the charging of a vehicle battery can take placeeither when the vehicle is running or when the vehicle is parked.Therefore, different charging modes can be provided, and chargingefficiency can be improved.

The detailed configuration of the transmission unit 101 may be describedin detail below with reference to detailed embodiments as shown in FIGS.1-6.

In some embodiments, as shown in FIGS. 1-6, the output unit may rotatewith one of the output shafts, such as the second output shaft 22, at adifferent speed. In other words, the output unit 221 and thecorresponding output shaft may rotate at different speeds independently.

In some embodiments, the output unit 221 may selectively engage one ofthe output shafts, and rotate together with the output shaft. In otherwords, the output unit 221 may engage one of the output shafts androtate together with the output shaft thereof. In some embodiments, theoutput unit 221 and one of the output shafts may rotate at differentspeeds.

In some embodiments, as shown in FIGS. 1-6, the output unit 221 may fitover one of the output shafts without particular limits in the presentdisclosure. In some embodiments, as shown in FIGS. 1-5, the output unit221 may fit over the second output shaft 22. In other words, the outputunit 221 and the second output shaft 22 may rotate at different speeds.

In some embodiments, as mentioned above, corresponding output unitsynchronizers 221 c may configure to synchronize the output unit 221with one of the output shafts.

In some embodiments, the output unit synchronizer 221 c may be disposedon one of the output shafts and engage the output unit 221. In otherwords, as shown in FIG. 1, when the output unit synchronizer 221 c is ina disengaged state, the output unit 221 and the second output shaft 22may rotate at different speeds. When the output unit synchronizer 221 cis in an engaged state, the output unit 221 may rotate together with thesecond output shaft 22.

In some embodiments, the output unit 221 may be an output idler gear,and the output idler gear 221 may fit over one of the output shafts. Theoutput idler gear 221 may mesh with the shift driven gear 74 of a mainreducer. In the present embodiments, the output unit synchronizer 221 cmay be the output idler gear 221 c, and the output idler gear 221 c mayconfigure to synchronize the output idler gear 221 with one of theoutput shafts, such as the second output shaft 22.

It should be noted that, the output idler gear 221 as the output unit221 and the output idler gear 221 c as the output unit synchronizer 221c are being applied in specific cases and may be schematic examplesprovided for better understanding the present disclosure, which may notbe construed as a limitation.

In some embodiments, the fixed output gear 211 may configure to fix onother output shafts. In the present embodiments, the output shaftsincludes a first output shaft 21 and a second output shaft 22. Theoutput unit 221 may fit over the second output shaft 22, and the fixedoutput gear 211 may be fixed on the first output shaft 21, which may notbe construed as a limitation.

The motor power shaft 3 may rotate together with one of the outputshafts according to embodiments of the present disclosure will bedescribed below with reference to FIGS. 1-6.

In some embodiments of the present disclosure, the motor power shaft 3may rotate together with one of the output shafts via a gear pair. Thegear mechanism has simple structure and is convenient for using in powertransmission. In addition, with the gear mechanism, a requiredtransmission ratio may be obtained and the power transmission may bereliable. The gear pair may include two meshed gears, a generator gear73 and a motor power shaft gear 31.

In some embodiments, the generator gear 73 may be fixed on one of theoutput shafts. In other words, the generator gear 73 is fixed on anoutput shaft. The output shaft and the output unit 221 may rotate atdifferent speeds or rotate together with each other. In someembodiments, the generator gear 73 may be fixed on the second outputshaft 22 without particular limits in the present disclosure. The motorpower shaft gear 31 may be disposed on the motor power shaft 3, and themotor power shaft gear 31 may configure to mesh with the generator gear73. In other words, power may transmit from the motor power shaft gear31 to the generator gear 73.

A reverse unit of the power transmission system 100 according toembodiments of the present disclosure may be described below in detail.

In some embodiments, the reverse unit includes a reverse output gear 72and a reverse idler gear. The reverse output gear 72 may configure torotate together or disengage from one of the shift driving gear, such asa shift driving gear 2 a. In some embodiments, the reverse output gear72 may rotate together with the shift driving gear, the power generatedby the engine 4 and/or the power generated by the first motor generator51 may transmit to the reverse output gear 72. In some embodiments, thereverse output gear 72 may disengage from the shift driving gear, andpower may not transmit to the reverse output gear 72.

In some embodiments, the reverse output gear 72 may selectively rotatetogether with the shift driving gear via reverse idler gears, such as afirst reverse idler gear 711, a second reverse idler gear 712 and athird reverse idler gear 713.

In the present embodiments, the reverse idler gear may configure torotate together with one of the shift driven gears and the reverseoutput gear may selectively rotate together with the reverse idler gear.In other words, in some embodiments, the reverse output gear 72 mayrotate together with the reverse idler gear, the power generated by theengine 4 and/or the power generated by the first motor generator 51 maytransmit to the reverse output gear 72. In some embodiments, the reverseoutput gear 72 may disengage from the reverse idler gear, and power maynot transmit to the reverse output gear 72.

In some embodiments, the reverse output gear 72 may synchronize with thereverse idler gear via the reverse synchronizer 72 c. In the embodimentsof the present disclosure, the reverse output gear 72 may configure torotate together with the reverse idler gear via a synchronization of thereverse synchronizer 72 c. In some embodiments, the reverse output gear72 and the reverse idler gear may rotate at different speeds when thereverse synchronizer 72 c is in a disengaged state.

In some embodiments, the reverse synchronizer 72 c and the output unitsynchronizer 221 c may share a shift fork mechanism. The reversesynchronizer 72 c may synchronize the reverse output gear 72 with thereverse idler gear. At the same time, the output unit synchronizer 221 cis in a disengaged state. The output unit synchronizer 221 c maysynchronizer the output unit 21 with one of the output shafts. At thesame time, the reverse synchronizer 72 c is in a disengaged state. Insome embodiments, as shown in FIG. 1, the engaging sleeve of the reversesynchronizer 72 c may move to the right to engage the third reverseidler gear 713, and the output unit synchronizer 221 c is in adisengaged state. In some embodiments, the engaging sleeve of the outputunit synchronizer 221 c may move to the left to engage the output unit221, the reverse synchronizer 72 c is in a disengaged state.

Therefore, both of the synchronization of the reverse synchronizer 72 cand the output unit synchronizer 221 c can be controlled by one shiftfork mechanism. The number of the shift fork mechanisms can be saved andthe power transmission system 100 can have a more compact structure, asmaller axial and diametric size, more convenient to arrange onvehicles.

In some embodiments, as shown in FIGS. 1-5, the reverse idler gear mayinclude the first reverse idler gear 711, the second reverse idler gear712 and the third reverse idler gear 713. Specially, the first reverseidler gear 711 may configure to mesh with one of the shift drivinggears, such as the second-gear shift driving gear 2 a. The first reverseidler gear 711 may rotate together with the second reverse idler gear712 in the same direction and the same velocity. The second reverseidler gear 712 may rotate together with the third reverse idler gear713, and the reverse synchronizer 72 c may configure to selectivelysynchronize the reverse output gear 72 with the third reverse idler gear713.

In some embodiments, the reverse output gear 72 and the third reverseidler gear 713 may be arranged coaxially. The reverse synchronizer 72 cmay be disposed on the reverse output gear 72 and to engage with thethird reverse idler gear 713 or the reverse synchronizer 72 c may bedisposed on the third reverse idler gear 713 and to engage with thereverse output gear 72. In some embodiments of the present disclosure,as shown in FIGS. 1-5, both of the reverse output gear 72 and the thirdreverse idler gear 713 are fitted over the motor power shaft 3, suchthat the reverse shaft can be saved and the transmission unit 101 canhave a more compact structure. In some embodiments, the reversesynchronizer 72 c may be disposed on the reverse output gear 72 toengage the third reverse idler gear 713, which may not be construed as alimitation.

In some embodiments, as shown in FIGS. 1-6, the first reverse idler gear711 and the second reverse idler gear 712 may form an integratedstructure so as to be a joint gear structure, such that the axial sizeof the first reverse idler gear 711 and the second idler gear 712 may bereduced and arrange on vehicles more conveniently.

The input shaft(s), the output shaft(s), the shift driving gears and theshift driven gears of the power transmission system 100 will bedescribed below with reference to embodiments shown in FIGS. 1-6.

In some embodiments, as shown in FIGS. 1-5, two input shafts areprovided. In the present embodiment, the plurality of input shaftsincludes a first input shaft 11 and a second input shaft 12. The secondinput shaft 12 may be hollow and the first input shaft 11 may be solid.One part of the first input shaft 11 may be inserted within the secondinput shaft 12, and the other part of the first input shaft 11 mayextend out of the second input shaft 12 along an axial direction of thesecond input shaft 12. The first input shaft 11 and the second inputshaft 12 may be arranged coaxially.

In some embodiments, two output shafts are provided. In the presentembodiment, the plurality of output shafts may include a first outputshaft 21 and a second output shaft 22. The first output shaft 21 and thesecond output shaft 22 may be arranged coaxially with the input shafts(such as the first input shaft 11 and the second input shaft 12). Boththe first output shaft 21 and the second output shaft 22 may be solid.

In some embodiments, the power transmission system 100 according toembodiments of the present disclosure may have six gear transmissiontypes. Specifically, odd number-gear shift driving gears may be arrangedon the first input shaft 11, while even number-gear shift driving gearmay be arranged on the second input shaft 12. The first input shaft 11may transmit power from gear pairs of odd-numbered gears, and the secondinput shaft 12 may transmit power from gear pairs of even-numberedgears.

In some embodiments, as shown in FIGS. 1-5, a first-gear shift drivinggear 1 a, a third-gear shift driving gear 3 a and a fifth-gear shiftdriving gear 5 a may be arranged on the first input shaft 11, and asecond-gear shift driving gear 2 a, and a fourth-sixth-gear shiftdriving gear 46 a may be arranged on the second input shaft 12. Each ofthe first-gear to fourth-sixth-gear shift driving gears 1 a, 2 a, 3 a,46 a, and 5 a may rotate together with a corresponding input shaft.

In some embodiments, a first-gear shift driven gear 1 b, a second-gearshift driven gear 2 b, a third-gear shift driven gear 3 b and afourth-gear shift driven gear 4 b may be disposed on the first outputshaft 21, and a fifth-gear shift driven gear 5 b and a sixth-gear shiftdriven 6 b may be disposed on the second output shaft 22. Each of theshift driven gears 1 b, 2 b, 3 b, 4 b, 5 b and 6 b may be fitted over acorresponding output shaft. Each of the shift driven gears and thecorresponding output shafts thereof may rotate at different speeds.

In some embodiments, the first-gear shift driving gear 1 a may mesh withthe first-gear shift driven gear 1 b to form one gear pair, thesecond-gear shift driving gear 2 a may mesh with the second-gear shiftdriven gear 2 b to form one gear pair, the third-gear shift driving gear3 a may mesh with the second-gear shift driven gear 3 b to form one gearpair, the fourth-sixth-gear shift driving gear 46 a may mesh with thefourth-gear shift driven gear 4 b to form one gear pair, the fifth-gearshift driving gear 5 a may mesh with the fifth-gear shift driven gear 5b to form one gear pair, and the fourth-and-sixth-gear shift drivinggear 46 a may mesh with the fifth-gear shift driven gear 6 b to form onegear pair and six pairs of gear pairs can be formed.

In the present embodiment, the fourth-gear gear pair and the sixth-geargear pair share the fourth-sixth shift driving gear 46 a, so that thenumber of shift driving gears can be reduced to make the powertransmission system 100 have a more compact structure.

As the shift driven gear is fitted over the corresponding output shaft,a synchronizer is provided to synchronize the shift driven gear and thecorresponding output shaft, thus achieving the object of powertransmission.

In some embodiments, as shown in FIG. 1 and FIGS. 1-5, the powertransmission system 100 includes a first-third gear synchronizer 13 c, asecond-fourth gear synchronizer 24 c, and a fifth-sixth gearsynchronizer 56 c.

In some embodiments, as shown in FIG. 1, the first-third gearsynchronizer 13 c is disposed on the first output shaft 21 and betweenthe first-gear shift driven gear 1 b and the third-gear shift drivengear 3 b. The first-third gear synchronizer 13 c may engage the firstoutput shaft 21 with the first-gear shift driven gear 1 b or thethird-gear shift driven gear 3 b, such that the shift driven gear mayrotate together with the corresponding output shaft, e.g., thefirst-gear shift driven gear 1 b and may rotate together with the firstoutput shaft 21, and the third-gear shift driven gear 3 b and may rotatetogether with the first output shaft 21.

In some embodiments, as shown in FIG. 1, the first-third gearsynchronizer 13 c includes an engaging sleeve. In some embodiments, theengaging sleeve of the first-third gear synchronizer 13 c may move tothe left so as to engage the third-gear shift driven gear 3 b with thefirst output shaft 21, such that the third-gear shift driven gear 3 bmay rotate together with the first output shaft 21. In some embodiments,the engaging sleeve of the first-third gear synchronizer 13 c may moveto the right so as to engage first-gear shift driven gear 1 b with thefirst output shaft 21, such that the first-gear shift driven gear 1 bmay rotate together with the first output shaft 21.

In some embodiments, as shown in FIG. 1, the second-fourth gearsynchronizer 24 c is disposed on the first output shaft 21 and betweenthe second-gear shift driven gear 2 b and the fourth-gear shift drivengear 4 b. The second-fourth gear synchronizer 24 c may engage thesecond-gear shift driven gear 2 b with the first output shaft 21 orengage the fourth-gear shift driven gear 4 b with the first output shaft21, such that the shift driven gear may rotate together with thecorresponding output shaft, e.g., the second-gear shift driven gear 2 bmay rotate together with the first output shaft 21, and the fourth-gearshift driven gear 4 b may rotate together with the first output shaft21.

In some embodiments, as shown in FIG. 1, the second-fourth gearsynchronizer 24 c includes an engaging sleeve. In some embodiments, theengaging sleeve of the second-fourth gear synchronizer 24 c may move tothe left so as to engage the second-gear shift driven gear 2 b with thefirst output shaft 21, such that the second-gear shift driven gear 2 bmay rotate together with the first output shaft 21. In some embodiments,the engaging sleeve of the second-fourth gear synchronizer 24 c may moveto the right so as to engage fourth-gear shift driven gear 4 b with thefirst output shaft 21, such that the fourth-gear shift driven gear 4 bmay rotate together with the first output shaft 21.

In some embodiments, as shown in FIG. 1, the fifth-sixth gearsynchronizer 56 c is disposed on the second output shaft 22 and betweenthe fifth-gear shift driven gear 5 b and the sixth-gear shift drivengear 6 b. The fifth-sixth gear synchronizer 56 c may engage thefifth-gear shift driven gear 5 b with the second output shaft 22 orengage the sixth-gear shift driven gear 6 b with the second output shaft22. The fifth-sixth gear synchronizer 56 c includes an engaging sleeve.In some embodiments, the engaging sleeve of the fifth-sixth gearsynchronizer 56 c may move to the left so as to engage the sixth-gearshift driven gear 6 b with the second output shaft 22, such that thesixth-gear shift driven gear 6 b may rotate together with the secondoutput shaft 22. In some embodiments, the engaging sleeve of thefifth-sixth gear synchronizer 56 c may move to the right so as to engagefifth-gear shift driven gear 5 b with the second output shaft 22, suchthat the fifth-gear shift driven gear 5 b may rotate together with thesecond output shaft 22.

In some embodiments of the present disclosure, the engine 4 may transmitpower to, or disengage from, the first input shaft 11 and the secondinput shaft 12 via a dual clutch 2 d.

In some embodiments of the present disclosure, as shown in FIGS. 1-5,the dual clutch 2 d includes an input terminal 23 d, a first outputterminal 21 d and a second output terminal 22 d. The engine 4 isconnected with the input terminal 23 d of the dual clutch 2 d. In someembodiments, the engine 4 is connected with the input terminal 23 d byat least one selected from a group consisting of a flywheel, a damper, atorsional disk, etc.

In some embodiments, the first output terminal 21 d is connected withthe first input shaft 11, such that the first output terminal 21 d mayrotate together with the first input shaft 11. In some embodiments, thesecond output terminal 22 d is connected with the second input shaft 12,such that the second output terminal 22 d may rotate together with thesecond input shaft 12.

In some embodiments, the input terminal 23 d may include a shell of thedual clutch 2 d, and each of the first output terminal 21 d and thesecond output terminal 22 d may include one driven disk of the dualclutch 2 d. In some embodiments, the shell is disengaged from the drivendisk, i.e., the input terminal 23 d is disengaged from the first outputterminal 21 d and is disengaged from the second output terminal 22 d.When the shell is to be engaged with one driven disk, the shell can becontrolled to engage with a corresponding driven disk, thus the shelland this driven disk may rotate together. In the present embodiment, theinput terminal 23 d may engage with one of the first output terminal 21d and the second output terminal 22 d to transmit power from the inputterminal 23 d to one of the first output terminal 21 d and the secondoutput terminal 22 d, to output the transmitted power.

In some embodiments, the shell may be engaged with two driven diskssimultaneously. In the present embodiment, the input terminal 23 d isengaged with both the first output terminal 21 d and the second outputterminal 22 d, and thereby power from the input terminal 23 d may betransmitted to the first output terminal 21 d and the second outputterminal 22 d so as to be output.

A person with ordinary skill in the art will appreciate that theengaging state of the dual clutch 2 d may be controlled according topractical condition, and that the engaging state may also be adjustedaccordingly based on a current transmission mode. In some embodiments,the input terminal 23 d may disengage from the two output terminalsincluding, for example, the first output terminal 21 d and the secondoutput terminal 22 d. In some embodiments, the input terminal 23 d mayengage with at least one of the two output terminals including, forexample, the first output terminal 21 d and the second output terminal22 d.

In some embodiments, the power transmission system 100 further includesthree power output shafts, i.e., a first output shaft 21, a secondoutput shaft 22, and a motor power shaft 3. These power output shafts, adifferential 75, and relationships therebetween may be described belowin detail with reference to FIGS. 1-5.

In some embodiments, the differential 75 may be disposed between a pairof front wheels 76 of the vehicle. In some embodiments, the differential75 may be disposed between a pair of rear wheels 77 of the vehicle. Thedifferential 75 may drive the wheels to the left or to the right whenthe vehicle is turning or running on a rough road, such that the wheelsmay roll with different angular speeds, and therefore driving wheels atboth sides of the vehicle may perform only rolling on the ground. Insome embodiments, a shift driven gear 74 of a main reducer may bedisposed on the differential 75, for example, the shift driven gear 74may be disposed on a shell of the differential 75. In some embodiments,the shift driven gear 74 may be a bevel gear, which may not be construedas a limitation.

In some embodiments, as mentioned above, the fixed output gear 211 andthe output unit 221, i.e., the output idler gear 221, may output thepower transmitted to the output shafts, such that both of the fixedoutput gear 211 and the output unit may mesh with the shift driven gearof a main reducer.

In some embodiments, as the output reverse output gear 72 may output thereverse power, the reverse output gear 72 may mesh with the shift drivengear 74.

The power transmission system 100 according to embodiments of thepresent disclosure may be used in various different conditions, such asa parking-charging condition (for example, charging the vehicle whilethe vehicle is parking), a running-charging condition (for example,charging the vehicle while the vehicle is running and both clutch partsof dual clutch 2 d are engaged), and the reverse mode.

In the parking-charging condition, the engine 4 is configured togenerate power and output the power to the first motor generator 51 viathe generator gear 73 and the motor power shaft gear 31, thereby drivingthe first motor generator 51 to generate electric power.

In some embodiments, as shown in FIGS. 1-5, in the parking-chargingstate, the engine 4 generates power and transmits the power to thesecond output shaft 22 via the first input shaft 11, one component ofthe fifth-gear gear pair and the second input shaft 12 therebetween andthe six-gear gear pair sequentially. The first motor generator 51 may bedriven to generate electric power as a generator by the power generatedby the engine 4 transmitted by the generator gear 73, the motor powershaft gear 31 and the motor power shaft 3 sequentially.

Therefore, charging the vehicle when the vehicle is parking may beachieved, and the number of charging modes is increased. In theparking-charging mode, the vehicle is not running, all power from theengine 4 may be used to charge the vehicle, thus providing a fastcharging performance and enhancing the charging efficiency.

In the running-charging condition, the input terminal 23 d is engagedwith the first output terminal 21 d and engaged with the second outputterminal 22 d simultaneously, a part of power generated by the engine 4may be output to one of the output shafts to drive the wheels of thevehicle, and the other part of power may be transmitted to the firstmotor generator 51 via the generator gear 73 and the motor power shaftgear 31, thus driving the first motor generator 51 to generate electricpower.

In the running-charging condition, as shown in FIGS. 1-5, a part ofpower generated by the engine 4 may be transmitted to the first motorgenerator 51 via the first input shaft 11, the fifth-gear gear pair, thegenerator gear 73 and the motor power shaft gear 31 sequentially, thusdriving the first motor generator 51 to generate electric power. Theother part of the power generated by the engine 4 may be output via thesecond input shaft 12 and one component of the second-gear gear pair andthe fourth-gear gear pair therebetween.

In the running-charging condition, as shown in FIG. 1, a part of powergenerated by the engine 4 may be transmitted to the first motorgenerator 51 via the second input shaft 12, the sixth-gear gear pair,the generator gear 73 and the motor power shaft gear 31 sequentially,thus driving the first motor generator 51 to generate electric power.The other part of the power generated by the engine 4 may be output viathe first input shaft 11 and one component of the first-gear gear pairand the third-gear gear pair therebetween.

It is known to those skilled in the art that, a conventional dual clutchgenerally has two gear parts, and only one gear part is used when thedual clutch is working. In the power transmission system 100 accordingto embodiments of the present disclosure, however, two gears parts ofthe dual clutch 2 d may be both engaged (for example, the input terminal23 d is engaged with the first output terminal 21 d and engaged with thesecond output terminal 22 d simultaneously) when the dual clutch 2 d isworking. In the present embodiment, a part of power from the engine 4may be output to wheels of the vehicle via one output shaft to drive thevehicle to run, and the other part of power from the engine 4 may betransmitted to the first motor generator 51 to drive the first motorgenerator 51 to generate electric power. In this way, transmission modesof the vehicle are increased, and charging the vehicle while the vehicleis running may be achieved.

In the power transmission system 100 according to embodiments of thepresent disclosure, a mechanical reverse mode, an electric reverse modeand a hybrid (both mechanic and electric) reverse mode may be achieved.

In the mechanical reverse mode, the reverse of the vehicle isaccomplished with power from the engine 4. Specifically, the engine 4generates power and transmits the power to the reverse idler gear, andthen transmits to the reverse output gear 72 via synchronization ofreverse synchronizer 72 c (synchronizing the reverse idler gear).

In the mechanical reverse mode, as shown in FIG. 1, power generated bythe engine 4 may transmit to the third reverse idler gear 713 via thesecond input shaft 12, the first reverse idler gear 711 and the secondreverse idler gear 712. The engaging sleeve of the reverse synchronizer72 c may move to the right to engage with the third reverse idler gear713, thus transmitting the power generated by the engine 4 to thereverse output gear 72 via the reverse idler gear.

In the mechanical reverse mode, as shown in FIG. 1, the reversesynchronizer 72 c may engage with the third reverse idler gear 713.

In the electric reverse mode, the reverse of the vehicle can be enabledwith power from the first motor generator 51. Specifically, the firstmotor generator 51 may generate power and transmit the power to anoutput shaft via the generator gear 73, so as to be output. Thegenerator gear 73 may dispose on the output shaft. In some embodiments,as shown in FIGS. 1-5, the output unit synchronizer 221 c may engagewith the output unit 221. Power generated by the first motor generator51 may transmit to the output unit 221 via the motor power shaft gear31, the generator gear 73 and the second output shaft 22, so as to beoutput. Only the output unit synchronizer 221 c is in an engaged statein this transmission passage.

In some embodiments, the first motor generator 51 may generate power andtransmit the power to the reverse output gear 72 via the reverse idlergear and a synchronization of the reverse synchronizer 72 c. In someembodiments, as shown in FIGS. 1-5, the output unit synchronizer 221 cmay disengage from the output unit 221, and the fifth-sixth gearsynchronizer 56 c may engage with the sixth-gear shift driven gear 6 b,at the same time, the reverse synchronizer 72 c may engage with thethird reverse idler gear 713, thus transmitting power generated by thefirst motor generator 51 to reverse output gear 72 via the motor powershaft gear 31, the generator gear 73, the sixth-gear gear pair, thesecond input shaft 12 and the reverse idler gear, so as to be output.The reverse synchronizer 72 c is in an engaged state and the fifth-sixthgear synchronizer 56 c may engage with the sixth-gear shift driven gear6 b in this transmission passage.

In the hybrid reverse mode, the reverse of the vehicle may be achievedwith the engine 4 and the first motor generator 51. The hybrid reversemode may be a combination of the above mechanical reverse mode and theelectric reverse mode.

In the hybrid reverse mode, the engine 4 may generate first power andtransmit the first power to the reverse idler gear, and then the firstpower may be transmitted to the reverse output gear 72 via asynchronization of the reverse synchronizer 72 c (synchronizing thereverse idler gear), so as to be output.

In addition, the first motor generator 51 may generate second power andtransmit the second power to the reverse idler gear via the generatorgear 73, and then the second power may be transmitted to reverse outputgear 72 via a synchronization of the reverse synchronizer 72 c. Thereverse synchronizer 72 c is in an engaged state and the fifth-sixthgear synchronizer 56 c may engage with the sixth-gear shift driven gear6 b in this transmission passage.

In some embodiments as shown in, for example, FIG. 1, the powertransmission system 100 in the hybrid reverse mode combines the abovemechanical reverse mode and the electric reverse mode. The engine 4 maytransmit the first power to the second input shaft 12 as the abovemechanical reverse mode described. The first motor generator 51 maytransmit the second power to the second output shaft 12 as the aboveelectric reverse mode described. The first power and the second powermay be coupled together before being output to the wheels. In someembodiments, the first power and the second power may be coupled at thesecond input shaft 12 and the coupled power may be transmitted to thewheels via the reverse idler gear and the reverse output gear 72 so asto reverse the vehicle.

In the hybrid reverse mode, the first motor generator 51 may adjust thespeed, such that the second input shaft 12 may synchronously receive thefirst power from the engine 4 and the second power from the first motorgenerator 51, to provide a smooth and harmonious power transmission.

As described, with the power transmission system 100 according toembodiments of the present disclosure, three reverse modes including themechanical reverse mode, the electric reverse mode and the hybridreverse mode may be achieved, thus increasing the reverse modes andfacilitating a user to shift within the three reverse modes according toa practical condition, and therefore different driving requirements maybe satisfied.

When the vehicle has sufficient electric power, the electric reversemode may be used. In the electric reverse mode, harmful exhaust gasescan be minimized, and the energy consumption can be reduced. It is knownto those skilled in the art that, an unskilled driver will take longertime and more maneuvers to park the vehicle at a predetermined position.Considering that the engine 4 may generate more harmful gases during alow-speed reverse process and that the engine 4 has relatively higherfuel consumption, because the engine is at an uneconomical rotatingspeed during the reverse process, the electric reverse mode of thepresent disclosure is highly effective in reducing fuel consumptionduring such a low-speed reverse process. In addition, with the generatorbeing used as a power source, harmful exhaust gases can be minimized,and the energy consumption in a low-speed reverse process can also bedecreased. Therefore, the fuel economy of the engine 4 may be enhanced.

When the vehicle has insufficient or relatively less electric power, themechanical reverse mode may be used. In a case that the vehicle needs tobe reversed quickly or that the vehicle needs to be reversed with alarger power, the hybrid reverse mode may be used, thus enhancing thepower of the vehicle and providing better driving experience to theuser.

It should be noted that, the above three reverse modes being applied inspecific cases may be schematic examples provided for betterunderstanding the present disclosure, which may not be construed thatthe described reverse mode should be applied when the vehicle is in thecorresponding case. It is well known to those skilled in the art that,in a specific condition, a corresponding reverse mode may be selectedaccording to specific requirements and a practical condition.

With the power transmission system 100 according to embodiments of thepresent disclosure, a number of the reverse modes of the vehicle areincreased, which provide a driver with more options to reverse thevehicle. In this way, the driver may be provided more driving fun andreverse of the vehicle in different road conditions may be satisfied.

In some embodiments, the power transmission system 100 further includesa second motor generator 52. With the second motor generator 52, thepower of the power transmission system 100 may be improved, and moretransmission modes can be provided.

In some embodiments, the second motor generator 52 may perform powertransmission with the shift driven gear 74 of the main reducer. Forexample, a gear may be disposed on a motor shaft of the second motorgenerator 52, and the gear is configured to directly mesh with the shiftdriven gear 74 so as to perform power transmission. In some embodiments,the second motor generator 52 is configured to connect with the firstinput shaft 11 or the first output shaft 21. In some embodiments, thesecond motor generator 52 may be integral with the differential 75. Insome embodiments, the engine 4 and the first motor generator 51 areconfigured to drive front wheels of the vehicle, and the second motorgenerator 52 may be a wheel-side motor and configured to drive rearwheels. In some embodiments, the second motor generator 52 may drive thepair of rear wheels via a reducing mechanism. In some embodiments, twosecond motor generators 52 are provided, and each second motor generator52 is configured to drive one rear wheel via a reducing mechanism.

In some embodiments, as shown in FIGS. 2-5, the power transmissionsystem 100 may include an electric differential lock unit. The electricdifferential lock unit may lock a pair of driving wheels when thevehicle is skidding, thus enhancing the antiskid performance and thepass performance of the vehicle.

In some embodiments, as shown in FIGS. 2-5, the electric differentiallock unit may include a third motor generator 201, a fourth motorgenerator 301 and an antiskid synchronizer 503. The engine 4 and/or thefirst motor generator 51 is configured to drive a first pair of wheels76, the third motor generator 201 and the fourth motor generator 301 areconfigured to drive a second pair of wheels 77, the first pair of wheels76 are one pair of the pair of front wheels and the pair of the rearwheels, and the second pair of wheels 77 are the other one pair of thepair of front wheels and the pair of the rear wheels. In someembodiments, as shown in FIGS. 2-5, the engine and the first motorgenerator 51 may drive the pair of front wheels, and the third motorgenerator 201 and the fourth motor generator 301 may drive the pair ofrear wheels.

In some embodiments, as shown in FIGS. 2-5, the third motor generator201 is configured to rotate together with one of the second pair ofwheels 77. In the present embodiment, the third motor generator 201 mayoutput power to this one wheel so as to drive this one wheel to rotate.In some embodiments, power from this one wheel may be transmitted to thethird motor generator 201, thus driving the third motor generator 201 togenerate electric power.

In some embodiments, the fourth motor generator 301 is configured torotate together with the other one of the second pair of wheels 77. Inthe present embodiment, the fourth motor generator 301 may output powerto the other one wheel so as to drive the other wheel to rotate. In someembodiments, power from the other wheel may be transmitted to the fourthmotor generator 301, thus driving the fourth motor generator 301 togenerate electric power. In some embodiments, as shown in FIGS. 2-5, thethird motor generator 201 is configured to rotate together with a leftrear wheel of the vehicle, and the fourth motor generator 301 isconfigured to rotate together with a right rear wheel of the vehicle.This embodiment is provided for example, and the present disclosureshould not be construed to be limited by this embodiment.

In some embodiments, the antiskid synchronizer 503 is configured toselectively synchronize the second pair of wheels 77, such that thesecond pair of wheels 77 may rotate together. In the present embodiment,the antiskid synchronizer 503 may synchronize the second pair of wheels77, i.e., the antiskid synchronizer 503 is in an engaged state, suchthat the second pair of wheels 77 may form a fixed engagement. In thisway, the second pair of wheels 77 may rotate together, without rotatingat different rotating speeds.

In some embodiments, when the antiskid synchronizer 503 is in adisengaged state, and the third motor generator 201 and the fourth motorgenerator 301 may drive corresponding wheels respectively, such that thecorresponding wheels may rotate at different rotating speeds, thus theobject that different wheels rotates at different speeds may beachieved. In some embodiments, when the antiskid synchronizer 503 is ina disengaged state, the third motor generator 201 and the fourth motorgenerator 301 may drive the second pair of wheels 77 to rotate at a samerotating speed.

With the power transmission system 100 according to embodiment of thepresent disclosure, the third motor generator 201 and the fourth motorgenerator 301 are provided and configured to drive the second pair ofwheels 77 respectively, and therefore the second pair of wheels 77rotating at different rotating speeds may be achieved. When one of thesecond pair of wheels 77 is skidding, the antiskid synchronizer 503 maysynchronize the second pair of wheels 77 such that the second pair ofwheels 77 rotate together. In this way, power output by two motors (forexample, the third motor generator 201 and the fourth motor generator301) or one motor (for example, the third motor generator 201 or thefourth motor generator 301) may be coupled to drive the second pair ofwheels 77 together, thus enhancing the antiskid capability and passingperformance of the vehicle.

The power transmission system 100 according to embodiment of the presentdisclosure includes the antiskid synchronizer 503, and therefore amechanical self-locking differential mechanism commonly used in an axle(such as a rear axle) a conventional power transmission system may beavoided. In addition to the functions of the antiskid synchronizer 503itself, the function of a mechanical self-locking differential mechanismis performed by the antiskid synchronizer 503, and therefore the powertransmission system 100 according to embodiments of the presentdisclosure may have a more compact structure and relatively lower cost.

The third motor generator 201, the fourth motor generator 301, andtransmission method thereof will be described below in detail withreferences to FIGS. 2-5.

In some embodiments, as shown in FIGS. 2-4, the third motor generator201 may perform power transmission with the corresponding wheel via agear mechanism. In some embodiments, the fourth motor generator 301 mayperform power transmission with the corresponding wheel via a gearmechanism.

The gear mechanism has a simple structure and is convenient for use inpower transmission. In addition, with the gear mechanism, a requiredtransmission ration may be obtained and the power transmission may bereliable. In some embodiments, the third motor generator 201 and thefourth motor generator 301 may perform power transmission withcorresponding wheel(s) via a same gear mechanism. In the presentembodiment, the gear mechanism is common, and the power transmissionsystem 100 may be highly symmetric, thus avoiding the center of gravitymoving to one side. With one common gear mechanism, the center ofgravity may be located right in the middle or substantially the middleof the two wheels, and both the stability and reliability of the powertransmission system 100 may be improved.

In some embodiments, as shown in FIGS. 3-5, the gear mechanism betweenthe third motor generator 201 and the corresponding wheel may include afirst gear 401, a second gear 402, a third gear 403, and a fourth gear404.

In some embodiments, the first gear 401 may be disposed on the firstoutput shaft 202 corresponding to the third motor generator 201, and thefirst gear 401 is configured to rotate together with the first outputshaft 202. In some embodiments, the first output shaft 202 may outputpower generated by the third motor generator 201. In some embodiments,the first output shaft 202 may transmit power generated by thecorresponding wheel to the third motor generator 201. In someembodiments, the first output shaft 202 and the third motor generator201 may share a same motor shaft. In some embodiments, the motor shaftof the first output shaft 202 and the motor shaft the third motorgenerator 201 may be two individual parts different from each other. Inthe present embodiment, the motor shaft of the first output shaft 202and the motor shaft the third motor generator 201 may be connected toeach other.

In some embodiments, a first drive shaft 204 is connected with a wheelcorresponding to the third motor generator 201, and the second gear 402is disposed on the first drive shaft 204 and configured to rotatetogether with the first drive shaft 204. The third gear 403 and thefirst gear 401 are configured to mesh with each other, and the fourthgear 404 and the second gear 402 are configured to mesh with each other.The third gear 403 and the fourth gear 404 are coaxially arranged andmay rotate together.

In some embodiments, as shown in FIGS. 2-4, the gear mechanism betweenthe fourth motor generator 301 and the corresponding wheel may include afifth gear 405, a sixth gear 406, a seventh gear 407, and an eighth gear408. The fifth gear 405 may be disposed on the second output shaft 302corresponding to the fourth motor generator 301, and the fifth gear 405is configured to rotate together with the second output shaft 302. Insome embodiments, the second output shaft 302 may output power generatedby the fourth motor generator 301. In some embodiments, the secondoutput shaft 302 may transmit power generated by the corresponding wheelto the fourth motor generator 301. In some embodiments, the secondoutput shaft 302 and the fourth motor generator 301 may share one motorshaft. In some embodiments, the motor shaft of the second output shaft302 and the motor shaft of the fourth motor generator 301 may be twoindividual parts different from each other. In the present embodiment,the motor shaft of the second output shaft 302 and the motor shaft ofthe fourth motor generator 301 may be connected to each other.

In some embodiments, a second drive shaft 304 is connected with a wheelcorresponding to the fourth motor generator 301, and the sixth gear 406is disposed on the second drive shaft 304 and configured to rotatetogether with the second drive shaft 304. The seventh gear 407 and thefifth gear 405 are configured to mesh with each other, and the eighthgear 408 and the sixth gear 406 are configured to mesh with each other.The seventh gear 407 and the eighth gear 408 are coaxially arranged andmay rotate together.

In some embodiments, the first gear 401 and the fifth gear 405 may havethe same structure, such as having the same size and the same number ofteeth. In some embodiments, the second gear 402 and the sixth gear 406may have the same structure, such as having the same size and the samenumber of teeth. In some embodiments, the third gear 403 and the seventhgear 407 may have the same structure, such as having the same size andthe same number of teeth. In some embodiments, the fourth gear 404 andthe eighth gear 408 may have the same structure, such as have the samesize and the same number of teeth. Therefore, versatility of the gearmechanism may be improved.

In some embodiments, the third gear 403 and the fourth gear 404 may befixed on the first gear shaft 501, and the seventh gear 407 and theeighth gear 408 may be fixed on the second gear shaft 502. In someembodiments, the third gear 403 and the fourth gear 404 may form asubstantial ladder shape or a joint gear structure. In some embodiments,the seventh gear 407 and the eighth gear 408 may form a substantialladder shape or a joint gear structure.

In some embodiments, as shown in FIG. 2, the antiskid synchronizer 503may be disposed on the first drive shaft 204 and configured toselectively engage with the sixth gear 406. In some embodiments, a gearring may be provided on a side of the sixth gear 406 facing the antiskidsynchronizer 503, and the antiskid synchronizer 503 may include anengaging sleeve to adapt to the gear ring. With the engagement of theantiskid synchronizer 503, the second pair of wheels 77 may rotatetogether.

In some embodiments, as shown in FIG. 3, the antiskid synchronizer 503may be disposed on the first output shaft 202 and configured toselectively engage with the fifth gear 405. In some embodiments, a gearring may be provided on a side of the fifth gear 405 facing the antiskidsynchronizer 503, and the antiskid synchronizer 503 may include anengaging sleeve to adapt to the gear ring. With the engagement of theantiskid synchronizer 503, the second pair of wheels 77 may rotatetogether.

In some embodiments, as shown in FIG. 4, the antiskid synchronizer 503may be disposed on the first gear shaft 501 and configured toselectively engage with the seventh gear 407. In some embodiments, agear ring may be provided on a side of the seventh gear 407 facing theantiskid synchronizer 503, and the antiskid synchronizer 503 may includean engaging sleeve to adapt to the gear ring. With the engagement of theantiskid synchronizer 503, the second pair of wheels 77 may rotatetogether.

In some embodiments, as shown in FIG. 5, the third motor generator 201may be connected coaxially with a corresponding wheel, and the fourthmotor generator 301 may be connected coaxially with a correspondingwheel. In some embodiments, both the third motor generator 201 and thefourth motor generator 301 may be wheel-side motors, thus shortening thetransmission passage, reducing the power transmission loss and enhancingthe transmission efficiency.

In some embodiments, as shown in FIG. 5, the antiskid synchronizer 503may be disposed on the first output shaft 202 corresponding to the thirdmotor generator 201, and configured to selectively engage with thesecond output shaft 302 corresponding to the fourth motor generator 301.With the engagement of the antiskid synchronizer 503, the second pair ofwheels 77 may rotate together.

The power transmission system 100 and the condition the powertransmission system 100 may be used will be described below withreference to FIGS. 1-5.

Embodiment 1

As shown in FIG. 1, the engine 4 is connected with the input terminal 23d of the dual clutch 2 d, the first output terminal 21 d of the dualclutch 2 d is connected with the first input shaft 11, and the secondoutput terminal 22 d of the dual clutch 2 d is connected with the secondinput shaft 12. The input terminal 23 d may be disengaged from both thefirst output terminal 21 d and the second output terminal 22 d, or theinput terminal 23 d may be engaged with one of the first output terminal21 d and the second output terminal 22 d, or the input terminal 23 d maybe engaged with both the first output terminal 21 d and the secondoutput terminal 22 d.

The second input shaft 12 may be a hollow shaft, and the first inputshaft 11 may be a solid shaft. The second input shaft 12 is coaxiallyfitted over the first input shaft 11, and a part of the first inputshaft 11 extends outside of the second input shaft 12 along an axialdirection of the second input shaft 12.

The first-gear shift driving gear 1 a, the third-gear shift driving gear3 a and the fifth-gear shift driving gear 5 a are disposed on the firstinput shaft 11 and configured to rotate together with the first inputshaft 11. The first-gear shift driving gear 1 a is positioned in theright of the fifth-gear shift driving gear 5 a, and the third-gear shiftdriving gear 3 a is positioned in the left of the fifth-gear shiftdriving gear 5 a.

The second-gear shift driving gear 2 a and the fourth-sixth-gear shiftdriving gear 46 a are disposed on the second input shaft 12 andconfigured to rotate together with the second input shaft 12.

The first output shaft 21 is arranged parallel to the two input shafts,i.e., the first and second input shafts 11, 12. The first-gear shiftdriven gear 1 b, the second-gear shift driven gear 2 b, the third-gearshift driven gear 3 b and the fourth-gear shift driven gear 4 b arefitted over the first output shaft 21. The first-gear shift driven gear1 b is configured to mesh directly with the first-gear shift drivinggear 1 a, the second-gear shift driving gear 2 a is configured to meshdirectly with the second-gear shift driven gear 2 b, the third-gearshift driving gear 3 a is configured to mesh directly with thethird-gear shift driven gear 3 b, and the fourth-sixth-gear shiftdriving gear 46 a is configured to mesh directly with the fourth-gearshift driven gear 4 b.

The first-third gear synchronizer 13 c, the second-fourth gearsynchronizer 24 c are disposed on the first output shaft 21, and thefirst-third gear synchronizer 13 c is positioned between the first-gearshift driven gear 1 b and the third-gear shift driven gear 3 b andconfigured to selectively synchronize the first output shaft 21 with thefirst-gear shift driven gear 1 b or the third-gear shift driven gear 3b. The second-fourth gear synchronizer 24 c is positioned between thesecond-gear shift driven gear 2 b and the fourth-gear shift driven gear4 b and configured to selectively synchronize the first output shaft 21with the second-gear shift driven gear 2 b or the fourth-gear shiftdriven gear 4 b.

The second output shaft 22 is arranged parallel to the two input shafts,i.e., the first and second input shafts 11, 12. The fifth-gear shiftdriven gear 5 b and the sixth-gear 6 b are fitted over the second outputshaft 22. The fifth-gear shift driven gear 5 b may mesh with thefifth-gear shift driving gear 5 a directly. The sixth-gear shift drivengear 6 b may mesh with the fourth-sixth-gear shift driving gear 46 adirectly. The fifth-sixth gear synchronizer 56 c is disposed on thesecond output shaft 22 and is configured to synchronize the secondoutput gear with the fifth-gear shift driven gear 5 b or the sixth-gearshift driven gear 6 b.

The fixed output gear 211 is fixed on the first output shaft 21 andconfigured to mesh with the shift driven gear 74. The output unit 221,i.e., output idler gear 221, is fixed on the second output shaft 22 andconfigured to mesh with the shift driven gear 74.

The output unit synchronizer 221 c, i.e., the output idler gearsynchronizer 221 c, is positioned to the right of the output idler gear221 and may engage with the output idler gear and with the second outputshaft 22. The generator gear 73 is fixed on the second output shaft 22.

The first reverse idler gear 711 and the second reverse idler gear 712are both fitted over the second output gear 22 to form a duplex gear.The first reverse idler gear 711 may mesh with the second-gear shiftdriving gear 2 a.

The motor power shaft 3 is disposed coaxially with the two input shaftssuch as the first and second input shafts 11, 12 and the two outputshafts such as the first and second output shafts 21, 22. The reverseoutput gear 72 and the third reverse idler gear 713 are fitted over themotor power shaft 3. The first motor gear 31 is fixed on the motor powershaft 3 and may mesh with the generator gear 73. The reversesynchronizer 72 c is disposed on the reverse output gear 72 and mayengage with the third reverse idler gear 713. The third idler gear 713may mesh with the second reverse idler gear 712. The first motorgenerator 51 and the motor power shaft 3 are coaxially connected.

A condition in which the power transmission system 100, according toembodiments of the present disclosure, may be used will be discussedbelow in detail with reference to FIG. 1.

Parking-Charging Condition

In the parking-charging condition, the engine 4 can drive the firstmotor generator 51 via two different transmission passages.

Transmission Passage 1.

The fifth-sixth gear synchronizer 56 c may engage with the fifth-gearshift driven gear 5 b. Power generated by the engine 4 may transmit tothe first motor generator 51 via the first input shaft 11, thefifth-gear gear pair, the second output shaft 22, the generator gear 73and the motor power shaft gear 31, thus driving the first motorgenerator 51 to generate electric power.

Transmission Passage 2

The fifth-sixth gear synchronizer 56 c may engage with the sixth-gearshift driven gear 6 b. Power generated by the engine 4 may transmit tothe first motor generator 51 via the second input shaft 12, thesixth-gear gear pair, the second output shaft 22, the generator gear 73and the motor power shaft gear 31, thus driving the first motorgenerator 51 to generate electric power.

In the parking-charging condition, charging the vehicle with a fixedvelocity ratio may be achieved, and the power transmission efficiencymay be increased. Those with ordinary skill in the art will appreciatethat the velocity ratio relates to parameters such as the rotating speedof the engine 4 in the parking state, the type of the first motorgenerator 51, and maximum rotating speed acceptable by the peripheralparts such as bearings, and so on. In the present disclosure, thevelocity ratio may be designed according to the above parameters and thepower transmission ratio may be flexibly designed, thus making maximumuse of the power from the engine 4 and achieving the object of fastcharging. In the parking-charging condition, power from the engine 4 maybe transmitted via a transmission passage consisting of the first inputshaft 11, the fifth-gear gear pair and the generator gear 73 or atransmission passage consisting of the second output shaft 22, thesixth-gear gear pair and the generator gear 73, and therefore the objectof charging with an optimal fixed velocity ratio may be achieved, andboth the charging efficiency and the fuel economy of the engine areimproved.

Pure Electric Condition

First Electric Condition

The output unit synchronizer 221 c engages the output unit 221, andpower generated by the first motor generator 51 is transmitted to theoutput unit 221 via the motor power shaft gear 31 and the generator gear73. This transmission passage has less transmission components andhigher efficacy.

Second Electric Condition

Power generated by the first motor generator 51 is transmitted to thesecond-gear gear pair or the fourth-gear gear pair via the generatorgear 73, the sixth-gear gear pair and the second input shaft 12.

Third Electric Condition

Power generated by the first motor generator 51 is transmitted to thefirst-gear gear pair or the third-gear gear pair via the generator gear73, the fifth-gear gear pair and the first input shaft 11.

In the electric condition such as the first electric condition or thesecond electric condition, power from the first motor generator 51 maybe transmitted to wheels of the vehicle via three power transmissionpassages having different velocity ratios, thus driving the vehicle torun. In cases when the first motor generator 51 is used to start, toaccelerate, to climb or to run, different velocity ratios may beselected accordingly to ensure that the first motor generator 51 has thehighest operation efficiency.

First First-Gear Hybrid Condition

The output unit synchronizer 221 c engages the output unit 221, andpower generated by the first motor generator 51 is transmitted to theoutput unit 221 via the motor power shaft gear 31 and the generator gear73. This transmission passage has less transmission components andhigher efficacy.

The first power generated by the engine 4 can be transmitted to any ofthe first-gear to fourth-gear gear pairs. The first power and secondpower are coupled at the driven gear 74, and then output together to thewheels of the vehicle.

The first power generated by the engine 4 can be transmitted to eitherthe fifth-gear or the sixth-gear gear pair. The first power and thesecond power are coupled at the second output shaft 22 and then outputtogether to the wheels of the vehicle.

In the hybrid reverse mode, the first motor generator 51 may adjust thespeed, such that the shift driven gear 74 or the second output shaft 22may synchronously receive the first power from the engine 4 and thesecond power from the first motor generator 51, to provide a smooth andharmonious power transmission.

First Second-Gear Hybrid Condition

In the first second-gear hybrid condition, the output unit synchronizer221 c is in a disengaged state. The power generated by the first motorgenerator 51 may transmit to the second input shaft 12 via the generatorgear 73 and the sixth-gear gear pair. The power generated by the engine4 may transmit to the second input shaft 12. The first power and thesecond power generated by the first motor generator 51 are coupled atthe second input shaft 12, and then transmitted to either thesecond-gear gear pair or the fourth-gear gear pair, so as to be output.In some embodiments, the power generated by the engine 4 may transmit toeither the first-gear gear pair or the third-gear gear pair via thefirst input shaft 11. Two powers are coupled at the first output shaft21 and then output together.

In the hybrid reverse mode, the first motor generator 51 may adjust thespeed, such that the second input shaft 12 or the first output shaft 21may synchronously receive the first power from the engine 4 and thesecond power from the first motor generator 51, to provide a smooth andharmonious power transmission.

First Third-Gear Hybrid Condition

In the first third-gear hybrid condition, the output unit synchronizer221 c is in a disengaged state. The power generated by the first motorgenerator 51 may transmit to the first input shaft 11 via the generatorgear 73 and the fifth-gear gear pair. The power generated by the engine4 may transmit to the first input shaft 11. The first power and thesecond power generated by the first motor generator 51 are coupled atthe first input shaft 11, and then transmitted to either the first-geargear pair or the third-gear gear pair. In some embodiments, the powergenerated by the engine 4 may transmit to either the second-gear gearpair or the fourth-gear gear pair via the first output shaft 21. Twopowers are coupled at the first output shaft 21 and then outputtogether.

In the hybrid reverse mode, the first motor generator 51 may adjust thespeed, such that the first input shaft 11 or the first output shaft 21may synchronously receive the first power from the engine 4 and thesecond power from the first motor generator 51, to provide a smooth andharmonious power transmission.

In the present disclosure, a person skilled in the art may flexiblyselect any of the above hybrid conditions and power transmissionpassages thereof according to practical requirements. With these hybridconditions, more driving fun may be provided to the users. In addition,the vehicle may be used in different road conditions, thus enhancingboth the power and the fuel economy of the vehicle.

First First-Gear Driving-Charging Condition

In the first first-gear driving-charging condition, the power generatedby the engine 4 can be transmitted to any of the first-gear tofourth-gear gear pairs. The output unit synchronizer 221 c may engagewith the output unit 221. Power generated by the corresponding wheel viathe output unit 221 and the second output shaft 22 may configure thegenerator gear 73 and the motor power shaft gear 31 rotate together withthe motor power shaft 3. In some embodiments, the first motor generator51 may drive to generate electric power by the power generated by thecorresponding wheel.

In some embodiments, the first power generated by the engine 4 can betransmitted to either the fifth-gear or the six-gear gear pair. At thesame time, the output unit synchronizer 221 c may engage with the outputunit 221. The first power generated by the engine 4 may transmit to thesecond output shaft 22 via the fifth-gear gear pair or the sixth-geargear pair. One part of the power may transmit to the output unit 221 todrive the wheels of the vehicle. The other part of the power maytransmit to the first motor generator 51 via the generator gear 73, themotor power shaft gear 31 and the motor power shaft 3, thus driving thefirst motor generator 51 to generate electric power.

First Second-Gear Driving-Charging Condition

In the first-gear driving-charging condition, one of the two gear partsof the dual clutch 2 d is engaged when performing power transmission,for example, the input terminal 23 d is engaged with the first outputterminal 21 d or engaged with the second output terminal 22 d. In thethird first-gear driving-charging condition, the input terminal 23 d isengaged with both the first output terminal 21 d and the second outputterminal 22 d, thus achieving a new driving-charging condition.

Condition 1

In the first second-gear driving-charging condition, the fifth-sixthgear synchronizer 56 c may engage with the fifth-gear shift driven gear5 b. The output unit synchronizer 221 c is in a disengaged state. A partof the power generated by the engine 4 may transmit to the first motorgenerator 51 via the first input shaft 11, the fifth-gear gear pair, thesecond output shaft 22, the generator gear 73 and the motor power shaftgear 31, thus driving the first motor generator 51 to generate electricpower. The other part of the power generated by the engine 4 maytransmit to the first output shaft 21 to drive the wheels of the vehiclevia the second input shaft 12, the second-gear gear pair or thefourth-gear gear pair.

Condition 2

In the first second-gear driving-charging condition, the fifth-sixthgear synchronizer 56 c may engage with the sixth-gear shift driven gear6 b. The output unit synchronizer 221 c is in a disengaged state. A partof the power generated by the engine 4 may transmit to the first motorgenerator 51 via the second input shaft 12, the sixth-gear gear pair,the second output shaft 22, the generator gear 73 and the motor powershaft gear 31, thus driving the first motor generator 51 to generateelectric power. The other part of the power generated by the engine 4may transmit to the first output shaft 21 to drive the wheels of thevehicle via the first input shaft 11, the second-gear gear pair or thefourth-gear gear pair.

In the present disclosure, a person skilled in the art may flexiblyselect any of the above hybrid conditions and power transmissionpassages thereof according to practical requirements. With these hybridconditions, more driving fun may be provided to the users. In addition,the vehicle may be used in different road conditions, thus enhancingboth the power and the fuel economy of the vehicle.

In the driving-charging conditions, a part of power from the engine 4may be transmitted via a passage consisting of the first input shaft 11,the fifth-gear gear pair, and the generator gear 73, or a passageconsisting of the second input shaft 12, the sixth-gear gear pair andthe generator gear 73, and therefore the object of charging with anoptimal fixed velocity ratio may be achieved, and both the chargingefficiency and the fuel economy of the engine 4 are improved.

Mechanical Reverse Condition

In the mechanical reverse condition, the reverse synchronizer 72 c mayengage with the third reverse idler gear 713, such that the powergenerated by the engine 4 may transmit to the reverse output gear 72 viathe second input shaft 12, the second-gear shift driving gear 2 a, thefirst reverse idler gear 711, the second reverse idler gear 712 and thethird reverse idler gear 713.

Electric Reverse Condition

In the electric reverse mode, the output unit synchronizer 221 c mayengage with the output unit 221, and the power generated by the firstmotor generator 51 may transmit to the output unit via the motor powershaft gear 31, the generator gear 73 and the second output shaft 22.

In the electric reverse mode, the output unit synchronizer 221 c is in adisengaged state, and the fifth-sixth gear synchronizer 56 c may engagewith the sixth-gear shift driven gear 6 b. At the same time, the reversesynchronizer 72 c may engage with the third reverse idler gear 713, suchthat the power generated by the first motor generator 51 may transmit tothe reverse output gear 72 via the generator gear 73, the sixth-geargear pair, the second input shaft 12 and the reverse idler gear.

Hybrid (Electric-Mechanic) Reverse Condition

In the hybrid reverse mode, the reverse synchronizer 72 c is in anengaged state and the fifth-sixth gear synchronizer 56 c may engage withthe sixth-gear shift driven gear 6 b. The power generated by the engine4 may transmit to the second input shaft 12, and the power generated bythe first motor generator 51 may transmit to the second input shaft 12via the generator gear 73 and the sixth-gear gear pair. The first powerand the second power are coupled at the second input shaft 12, and thenoutput together via the reverse idler gear. In the hybrid reverse mode,the first motor generator 51 may adjust the speed, such that the shiftdriven gear 74 may synchronously receive the first power from the engine4 and the second power from the first motor generator 51, to provide asmooth and harmonious power transmission.

In the parking-charging condition and the running-charging condition,the power generated by the engine 4 may transmit to the first motorgenerator 51 via the generator gear 73 and the motor power shaft gear31. The first motor generator 51 may always rotate along the originalrotating direction (the predetermined rotating direction such as theclockwise direction). When the first generator is regarded as the powerproducer, such as the pure electric conditions and the hybridconditions, the first motor generator 51 may always rotate along theoriginal rotating direction (the predetermined rotating direction suchas the clockwise direction). In the reverse conditions, when the powergenerated by the first motor generator 51 may output via a transmissionpassage consisting of the generator gear 73, the reverse idler gear andthe reverse output gear 72, the first motor generator 51 may alwaysrotate along the original rotating direction (the predetermined rotatingdirection such as the clockwise direction).

With the power transmission system 100 according to embodiments of thepresent disclosure, the first motor generator 51 may rotate along thepredetermined rotating direction in all the above-mentioned conditions.In other words, the first motor generator 51 may always rotate along thepredetermined rotating direction when functioning as a motor or as agenerator. Even during the power transmission system 100 switching fromone condition to the reverse condition, the rotating direction of thefirst motor generator 51 needs not to be changed. Therefore, the firstmotor generator 51 may always rotate along the predetermined rotatingdirection in all related conditions, such that problems of shock andinterruption due to direction change of the motor may be avoided, andthe life of the power transmission system 100 may be prolonged.

Embodiments 2-5

As shown in FIG. 2-5, the power transmission system 100 in the presentembodiment is substantially the same as that in Embodiment 1, with thefollowing exceptions that a rear-wheel driving mechanism, a third motorgenerator 201, a fourth motor generator 301 and an antiskid synchronizer503 are added respectively.

Embodiment 6

As shown in FIG. 6, the power transmission system 100 in the presentembodiment is substantially the same as that in Embodiment 1, with thefollowing exceptions that the engine 4, the dual clutch 2 d, the firstmotor generator 51 and the differential may be avoided.

Embodiments of the present disclosure further provide a vehicleincluding the above-identified power transmission system 100. Otherconfiguration such as the driving system, the turning system and thebraking system may be well known to those skilled in the art, thusdetails thereof are omitted herein.

Reference throughout this specification to “an embodiment,” “someembodiments,” “one embodiment”, “another example,” “an example,” “aspecific example,” or “some examples,” means that a particular feature,structure, material, or characteristic described in connection with theembodiment or example is included in at least one embodiment or exampleof the present disclosure. Thus, the appearances of the phrases such as“in some embodiments,” “in one embodiment”, “in an embodiment”, “inanother example,” “in an example,” “in a specific example,” or “in someexamples,” in various places throughout this specification are notnecessarily referring to the same embodiment or example of the presentdisclosure. Furthermore, the particular features, structures, materials,or characteristics may be combined in any suitable manner in one or moreembodiments or examples.

Although explanatory embodiments have been shown and described, it wouldbe appreciated by those skilled in the art that the above embodimentscannot be construed to limit the present disclosure, and changes,alternatives, and modifications can be made in the embodiments withoutdeparting from spirit, principles and scope of the present disclosure.

What is claimed is:
 1. A transmission unit for a vehicle, comprising: aplurality of input shafts, each of the input shafts having a shiftdriving gear thereon; a plurality of output shafts, each of the outputshafts having a shift driven gear configured to mesh with thecorresponding shift driving gear; a motor power shaft configured torotate together with one of the output shafts; an output unit configuredto rotate with the one or a different one of the output shafts at adifferent speed or configured to selectively engage with the one or thedifferent one of the output shafts so as to rotate together with theengaged output shaft; a reverse output gear configured to selectivelyrotate together with one of the shift driving gears via a reverse idlergear; and a reverse synchronizer configured to selectively synchronizethe reverse output gear with the reverse idler gear, wherein both thereverse output gear and the reverse idler gear are fitted over the motorpower shaft; and wherein in a parking state, the motor power shaft isconfigured to rotate together with one of the input shafts to drive afirst motor generator to generate electric power; and wherein theplurality of input shafts comprise a first input shaft and a secondinput shaft coaxially fitted over the first input shaft, and theplurality of output shafts comprise a first output shaft and a secondoutput shaft parallel to the first and second input shafts respectively;and wherein the shift driving gears on the plurality of input shaftscomprise: a first-gear driving gear disposed on the first input shaft, asecond-gear driving gear disposed on the second input shaft, athird-gear driving gear disposed on the first input shaft, a fifth-geardriving gear disposed on the first input shaft, and a fourth-sixth-geardriving gear disposed on the second input shaft; and wherein the shiftdriven gears on the plurality of output shafts comprise: a first-geardriven gear, a second-gear driven gear, a third-gear driven gear, and afourth-gear driven gear disposed on the first output shaft, a fifth-geardriven gear and a sixth-gear driven gear disposed on the second outputshaft; and wherein a first-third gear synchronizer disposed between thefirst-gear driven gear and the third-gear driven gear, a second-fourthgear synchronizer disposed between the second-gear driven gear and thefourth-gear driven gear, and a fifth-sixth gear synchronizer disposedbetween the fifth-gear driven gear and the sixth-gear driven gear. 2.The transmission unit according to claim 1, further comprising an outputunit synchronizer configured to synchronize the output unit with the oneor the different one of the output shafts.
 3. The transmission unitaccording to claim 2, wherein the output unit synchronizer is disposedon the one or the different one of the output shafts and configured toengage with the output unit.
 4. The transmission unit according to claim2, wherein the motor power shaft is configured to rotate together withthe one of the output shafts via a gear pair.
 5. The transmission unitaccording to claim 4, further comprising a motor power shaft gear fixedon the motor power shaft, and a generator gear fixed on the one of theoutput shafts and to mesh with the motor power shaft gear.
 6. Thetransmission unit according to claim 1, wherein the output unitcomprises an output idler gear fitted over the one or the different oneof the output shafts.
 7. The transmission unit according to claim 1,wherein the reverse synchronizer and an output unit synchronizer areconfigured to share a shift fork mechanism; wherein the output unitsynchronizer is in a disengaged state when the reverse synchronizersynchronizes the reverse output gear with the reverse idler gear;wherein the reverse synchronizer is in a disengaged state when theoutput unit synchronizer synchronizes the output unit with one of theoutput shafts.
 8. The transmission unit according to claim 1, whereinthe reverse idler gear being a third reverse idler gear, wherein thetransmission unit further comprises: a first reverse idler gearconfigured to mesh with the one of the shift driving gears; and a secondreverse idler gear configured to rotate together with the first reverseidler gear; wherein the third reverse idler gear is configured to meshwith the second reverse idler gear; and wherein the reverse synchronizeris configured to selectively synchronize the reverse output gear withthe third reverse idler gear.
 9. The transmission unit according toclaim 8, wherein the reverse output gear is coaxially arranged with thethird reverse idler gear; wherein the reverse synchronizer is disposedon one of the reverse output gear and the third reverse idler gear andto engage with the other of the reverse output gear and the thirdreverse idler gear.
 10. The transmission unit according to claim 9,wherein the reverse synchronizer is disposed on the reverse output gear.11. The transmission unit according to claim 8, wherein the firstreverse idler gear and the second reverse idler gear are formed as anintegrated joint gear structure.
 12. The transmission unit according toclaim 1, further comprising a fixed output gear fixed on another one ofthe output shafts.
 13. The transmission unit according to claim 12,wherein the output unit, the fixed output gear and the reverse outputgear are configured to mesh with a shift driven gear of a main reducerof the vehicle.
 14. The transmission unit according to claim 1, whereinthe reverse idler gear is configured to mesh with the second-geardriving gear; wherein a generator gear is fixed on the second outputshaft; wherein the output unit is fitted over the second output shaft.15. A power transmission system for the vehicle, comprising: thetransmission unit according to claim 1; and the first motor generatorconfigured to rotate together with the motor power shaft of thetransmission unit.
 16. A vehicle comprising the power transmissionsystem for the vehicle according to claim
 15. 17. A power transmissionsystem for the vehicle, further comprising: the transmission unitaccording to claim 1; an engine; and a dual clutch comprising: an inputterminal connected with the engine, a first output terminal coupled withthe first input shaft, and a second output terminal coupled with thesecond input shaft.